Donate Now Learn more about member benefits
Some water utilities already operate separate “purple pipe” recycled water programs that recycle some wastewater – but only well enough to use for irrigation and certain industrial uses. The purple pipe water flows through separate pipes from our drinkable water. The treated wastewater-turned-drinking water is heavily treated and would flow through the same pipes to homes and offices as regular drinking water.
While the city is still looking to expand its purple pipe system, the Pure Water program has in some ways put that on a back burner. While purple pipe water is cheaper for customers, it can only be used for certain things, like irrigation. It also requires a separate pipeline running next to existing pipes for drinking water, which is expensive.
But out in North County, a
group of water agencies is working to expand their purple pipe system while simultaneously beginning to explore efforts to make wastewater drinkable.
“Everybody in the county is looking at this now,” said Kimberly Thorner, general manager of Olivenhain Municipal Water District in Encinitas, a member of the North County group. “You kind of have to because what is going on with the drought.”
Each of the projects aimed at making wastewater drinkable will treat wastewater, send the treated water to a reservoir or underground, treat the water again and then send it to homes and businesses.
The obvious benefit of drinkable recycled water is that thinning water supplies are stretched further. Right now, much of the water officials want to reuse is imported from hundreds of miles away, used once and then dumped into the Pacific Ocean after being lightly treated.
“We recognize that wastewater – as it travels all the way down and is treated partially and put into the Pacific Ocean – is wasted water,” said Padre Dam general manager Alan Carlisle. “And we should be capturing every drop and repurposing it.”
Environmental groups agree, and several of them have endorsed the city’s Pure Water program for this very reason: to curb dumping.
The Padre Dam agency supplies water to about 100,000 people over 72 square miles from Santee to Alpine. If all goes according to plan, within five years, a fifth of the district’s water will come from treated wastewater.
In the city of San Diego, the reusable wastewater program has a long history and was once widely panned. Former Mayor Jerry Sanders once said, “Nooooo” and laughed nervously when
asked to drink some of the highly treated water in 2011.
The drought is helping to force everyone’s hand.
Fewer and fewer people react with “yuk” to the thought of purified sewer water. A
recent poll by Probe Research for the San Diego County Water Authority found support for reusing wastewater is now at 73 percent. Perhaps that’s because of the drought. Perhaps that’s because of stories noting that everyone already drinks “pee water.” Much of the region’s water comes from the Colorado River, which is used over and over and over again before it arrives in San Diego. City officials say their treated wastewater is purified water “of exceptional quality” and meets all federal and state drinking water standards.
The first part of the city’s Pure Water project will cost about $1 billion. That money will go to upgrade the North City water treatment plant, which is along the 805 near the University of California, San Diego.
Helminski, the water department’s assistant director, said the city is still working on putting together a financing plan for the project, which the City Council would have to approve. The water department hopes to start construction at North City in mid-2019.
From North City, 30 million gallons per day of treated water would be sent east to the 78 billion-gallon
reservoir behind the San Vicente Dam near Lakeside. There, the water would mingle with raw water from the Colorado River and Northern California. Water from San Vicente would eventually flow back to the city, be treated once more and then delivered to homes and businesses.
Later, the city would add more treatment capacity by building a new plant in Mission Valley to turn out 53 million additional gallons per day of treated wastewater. All told, by 2035, a third of the city’s drinking water supply is expected to be treated wastewater.
Helminski said the city is also looking at scenarios where it would not have to send the treated water all the way out to San Vicente, which would save several hundred million dollars because the city could lay fewer miles of new pipeline.
Instead, the city would skip storing water at San Vicente and just store it for a shorter period of time at smaller, nearby reservoirs – like
Lake Miramar and Lake Murray – before it flows back to the city to be treated once more before it’s used. There may be regulatory and public perceptions hurdles to jump before that happens because the treated wastewater would mix with smaller amounts of other water and be back in taps sooner.
This article relates to:
California Drought, Must Reads, Science/Environment, Water